In-Motion Ranging Sensor Calibration Using Travel-Path Targets
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Solution Overview
Problem
Existing ranging sensor systems face challenges in accurately measuring distances due to environmental changes and require periodic calibration, which is costly and often impossible during vehicle travel without additional equipment, leading to potential measurement errors.
Innovation Solution
A ranging sensor calibration system with multiple sensors facing different directions and a calibration processing unit that uses calibration targets along the vehicle's path to calibrate the sensors during travel, eliminating the need for separate high-accuracy ranging means.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If separate high-accuracy ranging means (such as ARF) is provided for calibration, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The existing ranging sensors are made to serve dual purposes: normal distance measurement and self-calibration. By using the same sensors for both functions and processing data through geometric relationships, the system eliminates the need for separate calibration equipment while maintaining calibration capability
Solution Approach 2:
The system performs self-calibration using its own ranging sensors and the geometric configuration of multiple sensors. The calibration process is autonomous, using the sensors' own measurement data and the known spatial relationships between sensors and calibration targets to correct measurement errors without external intervention
2Measurement precision
If calibration is performed only when vehicle is stopped, then measurement precision is maintained, but productivity and timing flexibility deteriorate
Solution Approach 1:
The calibration system transitions from a static, stopped-vehicle requirement to a dynamic, moving-vehicle capability. The geometric relationships between multiple sensors and calibration targets along the travel path enable calibration calculations to be performed continuously during vehicle motion, allowing calibration at appropriate timings without stopping
3Measurement precision
If ARF is used for calibration, then measurement precision is improved, but adaptability deteriorates due to limited ranging range
Solution Approach 1:
Instead of relying on a single calibration sensor with limited range, the system divides the calibration function across multiple ranging sensors positioned at different locations. Each sensor contributes to calibration of specific distance ranges, collectively covering the entire operational ranging spectrum of the stereo camera system
Data Source
AI summary
Provided is a ranging sensor calibration system that can execute a calibration operation during travel at low cost and without adding a special configuration. This ranging sensor calibration system is provided with a plurality of ranging sensors that are installed facing at least a first direction along a direction of travel of a vehicle and a second direction that is an opposite direction to the first direction, and are configured to be able to measure a distance; and a calibration processing unit that configures the plurality of ranging sensors. The calibration processing unit is configured to calibrate the plurality of ranging sensors on the basis of a distance between a plurality of calibration targets disposed near a travel path for the vehicle, a distance between the plurality of ranging sensors, and a distance measured by each of the plurality of ranging sensors.